LIVE • 2026-09-17
Most polluted cities right now
Top 30 cities ranked by current US EPA Air Quality Index across all 217 tracked locations. Refreshes every 30 minutes. The most polluted city right now is Riyadh, Saudi Arabia at AQI 389 (Hazardous). PM2.5 there is 62.9 μg/m³ (12.6x the WHO 2021 annual guideline of 5 μg/m³.
How this list is built
Each city’s AQI is calculated using the US EPA breakpoint formula on the dominant pollutant (usually PM2.5). When ground sensors are available we use them; otherwise we fall back to satellite + model fusion. See methodology for full detail and limitations.
Why these cities rank highest today
Common drivers behind the cities at the top: traffic emissions in dense megacities, coal and biomass heating in winter, industrial corridors, agricultural stubble burning, regional dust storms, and seasonal wildfire smoke transported across borders. Many South Asian and Middle Eastern cities sit near the top year-round; East Asian cities spike in winter; North American and Southern European cities spike during wildfire season.
What to do if your city is on this list
- Limit outdoor exertion when AQI is above 150; avoid it entirely above 200.
- Wear a properly fitted N95 / KN95 mask outside if AQI exceeds 150.
- Keep windows closed and run a HEPA air purifier indoors. Cheap DIY box-fan + filter setups work well.
- Sign up for free email alerts so you know when air quality crosses your chosen threshold.
See also: cleanest air today · highest PM2.5 · highest PM10 · highest ozone · highest NO2 · PM2.5 guide · methodology.